Pump or compressor



Dec. 16, 1941. o. E. CLARK 2,266,003

PUMP OR COMPRESS OR Filed Oct. 4, 1940 5 Sheets-Sheet l ATTORNEY Dec; 16, 1941. o. E. CLARK PUMP OR COMPRESSOR Filed Oct. 4, 1940 5 Sheets-Sheet 2 Dec.'1e, 1941. o. E. CLARK 2,266,003

PUMP OR COMPRESSOR Filed Oct. 4, 1940 5 Sheets-Sheet 3 I l f5 I l 2;; fag? 7/ Y l m36 .I x 7.? .LQ/ 4% 1` (5,3 l 74 7 3 7 7f3, 5'7'7 I1 wir".

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lin- E- Dec. 16, 1941. Q E, CLARK 2,266,003

PUMP QR COMPRES SOR Filed Oct. 4, 1940 5 Sheets-Sheet 4 )l ATTORNEY Dec. 16, 1941. o. E. CLARK I PUMP 0R COMPRESSOR Filed Oct. 4, 1940 5 Sheets-Sheet 5 INVENTOR ATToRN'EY Patented Dec. 16, 1941 UNITED STATES PATENTv OFFICE PUMP R CQMPRESSOR mar E. ,Clark Highland Park, Mich.

Application October 4, 1940, Serial No. 359,629 14 claims. (c1. 10s-161) `relatively lower` delivery volume at a relatively. higher pressure or vice versa responsive to anychange of pressure against which the pump operates.

With the foregoing in view, the primary object of the invention is to provide a hydraulic pump adapted to deliver a. variable volume of fluid at a pressure which varies inversely proportional to the volume delivered wherein the said volume of fluid delivered is variable automatically responsive to the pressure against which the pump operates.

line a-iof Fig. 3.

Fig. 3 isla fragmentary longitudinal sectional view of the adjusting sleeve employed to adjust4 the torsional pump pressure regulating spring anchored to the main shaft and to the eccentric shaft. l

Fig. 4 is a cross sectional view taken on the Fig. 5 is a cross sectional view taken on the line 5-5 of Fig. 2 showing a preferred construction of the anchorage of the torsional pump pressure regulating spring to the eccentric shaft.

Fig. 6 is a detailed sectional view taken on the line 6;-6 of Fig. 1 showing intake and exhaust valve mechanism preferably employed for each cylinder.

Fig. 7 is a vertical sectional view taken on the line lI--l of Fig. 2 showing wrench means employed 'to adjust the torsional spring pressure between the main and eccentric shafts.

Fig. 8 is a rear elevational view of the pump showing the suction and discharge conduit sys- Another object of the invention is to provide a lwdraulic pump in which the stroke of its pistons and volume of uid delivered vary automatically and instantaneously from a predetermined minimimum to a predetermined maximum Aresponsive to the pressure against which the pump operates and including means for regulating the pressure at which the stroke of the pump pistons and the volume of fluid delivered thereby vary. Y

Another object of the invention is to providel a simple, inexpensive-to-rnanufacture hydraulic pump having an automatically variable delivered volume and delivery pressure and wherein the delivered volume is inversely proportional to the delivery pressure, the said pump requiring a. constant horespower to operate regardless of the pressure against which .it operates within the limits of its capacity.

Other objects of the invention will become apparent by reference to the following detailed.

description taken in connection with the accompanyng drawings, in which:

Fig. l is a vertical sectional View of a fourcylinder pump embodying the invention taken on the line I-I of Fig. 2.

Fig. 2 is a longitudinal sectional view of theA pump disclosed in Fig. 1 taken on the line 2-2 thereof looking in the direction indicated by the arrows.

tem preferably employed.

Fig. 9 is a side yelevational 'view of the pump also showing the suction and discharge conduit system employed. v

Although the illustrative embodiment of the invention disclosed in the drawings and described in detail has four cylinders, obviously, the invention may be practiced in 4, 6, 8 or more cylinder embodiments or with any reasonable and practical number of cylinders; the drawings and dscription herein being intended to be illustrative and not limiting in this and other respects.

Referring now to the drawings wherein like numerals refer to like and corresponding parts throughout the several views, the illustrative em-f bodiment of the invention disclosed comprises, -in general, a main-pump casting I0 having four radially .disposed cylinders Il formed therein into which are reciprocatingly mounted pistons I2, three of which are connected by connecting rods I3 to a master connecting rod hub |40 of the master connecting rod I 4 connected tothe other or fourth piston I2, the said master connecting -rod hub |40 being mounted on a master wrist pin I5 preferably formed integral with and eccentric to an eccentric shaft I 6 mounted g for turning approximately 180 degrees axially within a :nain shaft I'I on a needle bearingv I8 at one end and the sleeve bearing I9 at the other end. The said main shaft I'I is mounted for rotal.- tion on ball bearings 20 and 2| within a housing 22 secured to the main pump body casting I0 by suitable socket head studs 23. A counterweight 24 is keyed on the forwardly extending endv of the master wrist pin I5 and is of suitable weight and proportions to maintain dynamic balance of the moving parts of the pump. A torsional pump pressure regulating spring 25 is anchored at one end to the eccentric shaft I6 by means of a spring anchor arm 26 and is anchored at its other end to the main shaft I1 by means of a pump pressure regulating spring adjustment collar 21 as hereinafter described in detail. Each cylinder II is provided with an intakev valve 28 and a discharge `valve 29 preferably as indicated inFig. 6. f

The main pump casting I0 preferably has a base |00 an intake conduit 30 formed along the top and bottom thereof communicating with the` intake valves 28 and preferably has a discharge conduit 3I formed along each side thereof communicating with the discharge valves 20. The intake conduits 30 in the top and bottom of the main pump casting I0 are preferably connected together by a bent flared end tubing 33. One of the intake conduits 30 and one of the discharge conduits 3 I in the main pump casting I0 are each provided with suitably threaded female intake and discharge line connecting fittings 34 and 35 respectively integrally cast with the main pump casting I0 as best shown in Figs: 1 and 8. Figs. 1, 2, 6, 8 and 9 show clearly the conduit and valve system preferably employed in the illustrative embodiment of the invention disclosed in the drawings. Where it has been necessary to bore the main pump casting I0 to form cylinders, valve compartments, valve ports, and the like, the castingv I0 has been plugged by employing suitable flanged socket head plugs 36 and washers 31 or taper threaded socket plugs 38.

The said cylinders II formed in the main casting I0 are preferably provided with suitable liners 39 as indicated in Figs. 1 and 2. The connecting rods I3 are connected to the master connecting rod hub I40 by suitable wrist pins 40 and to the pistons I2 by a'ball and socket connection generally designated by the numeral 4I throughout the drawings. The master connecting rod I4 is rigidly connected at its inner end to its hub |40 by such means as the socket head studs 42 and is connected at its outer end to a piston I2 by means of a ball and socket connection 4I. The employment of ball and' socket connections 4I between the pistons I2 and connecting rods I3 and-I4 compensates for any slight misalignment which may occur during manufacture and assembly.

The center B of the master wrist pin I5 formed integral with and eccentric to the eccentric shaft I6 is permitted to turn 180 degrees in -the direction indicated by the dotted line arrow 43 in Figs. 1 and 5 around the center A of the main shaft I1 until the center B of the master wrist pin `I5 takes the position indicated `by the letter C. While the eccentric shaft I6 is turning within the -main shaft I1,- the said center B of the master wrist pin I5 follows a path indicated by the dot and dash line 80 as shown in Figs. 1 and 5.

y The said turning movement of the master wrist pin I5 is permitted by the winding of the torsional pump pressure regulating spring 25 responsive to the pressure against which the pump operates which induces a torque between the eccentric shaft I6 and the main shaft I1 when the main shaft I1 is rotatedin the direction indicated by the full line arrow 44 shown in Figs. 1 and 5 by suitable power means applied to its extended end |10. When the pump is not operating or operating under a pressure less than required respect to the center A of the main shaft I1 is maximum. The eccentric shaft I6 and the torsional 'pump pressure regulating spring anchor arm 26 extending radially outward from the center D of the said eccentric shaft I6 and disposed in a semicircular slot 45 in the main shaft I1 are urged by the said torsional pump pressure regulating spring clockwise. as viewed in Fig. l and counterclockwise as viewed in Fig. 5 until the said spring anchor arm 26 rests against the shoulder or radial face 46 thereof.

As the pressure against which the pump operates increases from a relatively low pressure to a relatively high pressure, the torque between the eccentric shaft I6 and the main shaft I1 increases until it begins to wind the torsional pump pressure regulating spring 25 whereupon the said eccentric shaft I6 begins to turn about its center D in the direction indicated by the dotted line arrow 43 in Figs. 1 and 5 and the said anchor arm 26 moves from the radial shoulder or face 46 of the main shaft I1 toward the radialshoulder or face 460 of the main shaft I1 located 180 degrees counter to the rotation of the main shaft I1 from the said radial shoulder or 'face .46. When the said pressure against which the pump operates becomes maximum, the eccentric shaft I6 completes its 180 degree turning movement and the said pump pressure regulating spring anchor arm 26 comes to rest against the said shoulder or face 460 of the main shaft I1 as indicated by the dotted line showing of the anchor arm 2li-and hooked end 41 of the torsional spring 25 in Fig. 5.

During the turning of the said eccentric shaft I6 about its center D while the pressure against which the pump is operating increases from a minimum to a maximum, the eccentricity of the center B of the master wrist pin I5 with respect to the center A of the main shaft I1 decreases in inverse proportion to the said pressure against which the said pump operates until the said center B of the said master wrist pin I5 reaches the point C whereat the eccentricity thereof is at a minimum with respect to the center A of the said main shaft I1. Therefore, it is obvious that the reducing of the eccentricity of the eccentric shaft I6 and the center of the master wrist pin I5 with respect to the center of the main shaft I1 responsive to the increase cf pressure against which the pump operates varies the stroke of the pistons I2 with a corresponding variation in volume delivered and the volume delivered by the pump varies inversely proportional to the pressure against which the pump operates and vice versa. I

The torsional pump pressure regulating spring 25 is anchored at one end to the eccentric lshaft I6 by hooking the end 41 thereof over the outer grooved end 48 of the spring anchor arm 26 which is threaded diametrically into and extends radially from the eccentric shaft I6. 'Ihe said spring anchor arm 26 is preferably cylindrical in shape and is disposed in a semi-circular slot 45 in the main shaft I1 as shown in Figs. 2 and 5. The other end of the said torsional pump pressure regulating spring 25 is hooked and beveled at 49 to engage the axially angular face 6l of the pump pressure regulating spring adjustment collar 21.

The said pump pressure regulating spring ad-V justment collar 21 is fixed to the main shaft I1 by a suitable adjustment pin I which extends through one of the radially disposed adjustment pin apertures 52 in circumferentally spaced relationship around the said collar 21 and into one of the radially disposed adjustment pin bores 53 circumferentially spaced around the periphery of the said main shaft I1.

The pressure against which the pump delivers a maximum volume of fluid is regulated by the torsional adjustment of the pump pressure regulating spring 25 which is accomplished by first removing the spring adjustment cover plate 54 secured over a suitable `rectangular aperture 55 in the housing 22 by the socket head screws 56.

A suitable mushroom head lever wrench 51 is then inserted in one of the shouldered wrench apertures 58 as indicated in Fig. '1-,the adjustment pin 5| is removed, the collar is turned up or released back as desired until thedesired torsional pump pressure regulating spring tension is attained, the adjustment pin 5| is then inserted in any convenient registering adjustment pin aperture 52 in the pressure regulating spring adjustment collar 21 and the radially disposed adjustment pin bores 53 in the mainshaft I1, and the cover plate 54 is replaced.

12 against its valve seat 1I. Although the foregoing valve mechanism is preferred, obviously,

The front of the main pump casting |20 has an opening therein surrounded by an annular collar 59 covered bya cover plate 60 secured to the said collar 59 by suitable socket head studs 6|. A gasket 62 disposed between the end face of the said collar 59 and the cover plate 60 prevents lubricant from within the pump preferably maintained at the level indicated by the numeral 63 in Fig. 1 from leaking out therefrom.

The rear end of the housing 22 having theextended |10 of the main shaft I1 extending therefrom is preferably supported on vertical legs 220 formed integral with the base |00 and has a suitably apertured annular closure 64 secured to 'the end face thereof by means of socket head studs 65. A gasketY 66 disposed between the end face of the rear end of the housing 22 and the closure 64 prevents lubricant within the said housing 22 from leaking out therefrom. The said closure 64 is formed with suiiicient space therein to accommodate an oil seal 61 which .is disposed around the portion 68 of said main shaft I1 as shown in Fig. 5. The said closure V64 also has an inwardly disposed annular collar 69 which is employed to securethe outer race of the ball bearing 2| against a radially; inwardly projecting shoulder 10 formed within the said housing 22.

Referring now to Fig. 6, each of the intake and discharge Nalves 28 and 29 disclosed comprise a valve seat 'II against which a ball valve member 12 is constantly urged by a spring loaded ball valve thrust plunger 13 having la concavcd end 14 for engaging the said ball valve member 12 and urging it centrally toward and against the said valve seat 1|. the said ball valve thrust plunger 13 is telescoped within a h6llow guide member 15 having many other types of valve means .may be employed.

For example, assume that a pump is constructed in accordance with the instant invention having four cylinders and a maximum piston stroke at low pressure of 1",v and, employing a 3 horsepower motorl at 1200 R. P. M., the said pump will deliver 9 gallons per minute when the pressure against which it operates is 1666# or less. If the said pump is constructed so that its minimum piston stroke is .333", then, as the pressure against which it operates is increased above 1666# up to 5000#, its eccentric shaft I6 turns within the main shaft I1 so that the center B of the master wrist pin I5 thereof travels from its positionl of maximum eccentricity with respect to the center A of the main shaft I1 along the path indicated by the dot and dash of the wrist pin I5 with respect to the mainshaft I1 becomes reduced responsive to an increase of pressure against which the pump operates, the length ofthe stroke of the pistons I2 becomes reduced, and the 'volume delivered by the pump is reduced from the maximum of 9 gallons per minute at a pressure of 1666# to a minimum of 3v gallons per minute at a pressure of 500046.l Conversely, as the pressure against which the pump Voperates decreases.. the length of the stroke of its pistons I2 increase which increases the volume of fluid delivered thereby.

In any one designof pump, the maximum and minimum pressure responsive to whichthe volume of fluid delivered by the pump varies may be regulated by adjusting the torsional'resistance of the pump pressure regulating spring 25 as The stem portion of hereinbefore described in detail. Also, the operating pressures responsive to which the volume of uid delivered changes 1automaticallymay Abe changed radically over a rather wide range in any pump embodying the invention by merely changing the pump pressure regulating spring 25 to a weaker or a stronger one, all according to the` operating pressures desired. Thus one design of Vpump may/be applied to a wide range.of uses and requirements.

The invention has been described herein as a pump, however, it is obvious that the invention is also usable as a compressor for compressing air, gases and the like, and, it is intended that the specification and claims hereinbe construed accordingly., Y Y

Although but one illustrative embodiment of the invention has been disclosed and described in detail, it is obvious that many changes may be made in the size, shape, arrangement and detail of the various elements of the invention without departing from the spirit and scope of the invention as dened by the appended claims.

I claim:

1. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a drive shaft and an eccentric shaft turnable within the said drive shaft when the said drive shaft rotates, a master Wrist pin on said eccentric shaft eccentric to the center 'thereof and to the center of the said driveshaft, resilient means constantly urging said eccentric shaft to turn with respect to said drive shaft and move said master wrist pin to a position of maximum eccentricity with respect to said drive shaft, the said resilient means permitting the said eccentric shaft to turn to a position wherein the said master wrist pin assumes a position of less eccentricity with respect to the said drive shaft responsive to pressure against which the pump operates.

2. A pump or compressor comprising a, plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a drive shaft and an eccentric shaft turnable within the said drive shaft when the said drive shaft rotates, a master wrist pin on said eccentric s haft eccentric to the center thereof and to the center of the said drive shaft, a ltorsional spring connected at one end to the said drive shaft and at the other end to the eccentric shaft constant,- ly urging said eccentric shaft to turn with respect to said drive shaft and move said master wrist pin to a position of maximum eccentricity with respect to said drive shaft, the said torsional spring permitting the said eccentric `shaft to turn to a position wherein the said master wristpin assumes a position of less eccentricity with respect'to the said drive shaft responsive to torque developed by the pressure against which the pump operates.

3. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a drive shaftand an eccentric shaft turnable within the said drive shaft when the said drive shaft rotates, a master wrist pin on said eccentric shaft eccentric to the center thereof and to the center of the said drive shaft, resilient means constantly urging said eccentric shaft to turn with respect to said drive shaft and move said master wrist pin to a position of maximum eccentricity with respect to said drive shaft, the `said resilient means permitting the said eccentric shaft to turn to a position wherein the said master Wrist pin assumes apposition of less eccentricity with respect to the said drive shaft responsive to pressure against which the pump operates, and means for adjusting the resiliency of the said resilient means whereby to vary the pump pressure responsive to which the said eccentricity of the master wrist pin becomes reduced.

4. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a drive shaft and an eccentric shaft turnable within the said drive shaft when the said drive shaft rotates, a master wrist pinon said eccentric shaft eccentric to the center thereof and to the center of the said drive' shaft, a torsional spring connected at one end to the drive shaft and -at the other end to the eccentric shaft constantly urging said eccentric shaft to turn with respect to said drive shaft and move said masterwrist pin to a position of maxi- I mum eccentricity with respect to'said drive shaft,

the said torsional spring permitting the said ecresponsive to torque developed by the pressure against which the pump operates, and means for adjusting the resiliency of the said torsional spring whereby to vary the pump pressure responsive to which the said eccentricity ofthe master wrist pin becomes reduced.

5. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a drive shaft, an eccentric shaft turnable within said drive shaft when said drive shaft rotates, a master Wrist pin extending from said eccentric shaft eccentric to the center thereof and to the center of the said drive shaft, the eccentricity of the master wrist pin with respect to the center of the said drive shaft changing as the eccentric shaft turns with respect to the said drive shaft, means connecting the said pistons to the vsaid master wrist pin, and resilient means connecting said ececntric shaft to sidirive shaft constantly urging the eccentric slitfto turn with respect to the drive shaft to a position of maximum eccentricity of the said master wrist pin with respect to the said drive shaft, said resilient means permitting the said eccentric shaft to turn responsive to the pressure against which the pump operates to a position of 'less eccentricity of the said master Wrist pin with respect to the said main shaft whereby to automatically vary the volume delivered by the said pump responsive to the pressure against which it operates.

6. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a drive shaft, an eccentric shaft turnable within said drive shaft when said drive shaft rotates, a master wrist pin extending from said eccentric shaft eccentric to the center thereof and to the center of the said drive shaft, 'the eccentricity of the master wrist pin with respect tothe center of the said drive shaft changing as the eccentric shaft turns' with respect to the said drive shaft, means connecting the said pistons to the saidmaster wrist pin, anda torsional spring connecting said eccentric vshaft to said drive shaft constantly urging the eccentric shaft to turn with respect to the drive shaft to a position of maximum eccentricity of the said master wrist pin with respect to theisaid drive shaft, said torsional spring permitting the said eccentric shaft to turn responsive to the pressure against which the pump operates to a position of less eccentricityl of the said master Wrist pin with respect to the said main shaft whereby to automatically vary the volume centric sha-ft to turn to a position wherein the said master wrist pin assumes a position of less eccentricity with respect to the said drive shaft Adelivered by the said pump responsive to the pressure against which it operates.

7. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a drive shaft, an eccentric shaft turnable within said drive shaft whe aid drive shaft rotates, a master wrist pin extending from said eccentric shaft ececntric to the center thereof and to the center of the said drive shaft, the eccentricity of the master wrist pin with respectto the center of the said drive shaft changing as the eccentric shaft turns with respect to the said drive shaft,

Ymeans connecting the said pistons to the said master wrist pin, resilient means connecting `said eccentric shaft to said drive shaft constantly urging the eccentric shaft to turn with respect to the drive shaft to a position of maximum eccentricity pressure against which the pump operates to a position of less eccentricity of the said master wrist pin with respect to the said main shaft i whereby to automatically vary the volume delivshaft, an eccentric shaft turnable within said drive shaft when said drive shaft rotates, a master wrist pin extending from said eccentric shaft eccentric to the center thereof and to the center of the said drive shaft, the eccentricity of the master wrist' pin with respect to the ecnter of the-said drive shaft changing as the eccentric shaft turns with respect to the said drive (shaft, means connecting said pistons to the said master wrist pin, a torsional spring connecting the said eccentric shaft to said drive shaft constantly urging the eccentric shaft to turn with respect to the drive shaft to a position of maximum eccentricity of the said master wrist pin with respect to the said drive shaft, said torsional spring permitting the said eccentric shaft to turn responsive to the pressure against which the pump operates to a position of less eccentricity of the said master wrist pin with respect Ato the said main shaft whereby to automatically vary the volume delivered by the said pump responsive to torque developed by the pressure against which it operates, and means for adjusting the said torsional spring to regulate the pressure responsive to which the volume delivered by the said pump automatically reduces.

9. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a rotat-l ing shaft and an eccentric carried by said rotating shaft turnable with respectto the said rotating shaft during the rotation thereof to positions of more or less eccentricity with respect thereto, said pistons being connected to said eccentric, torsional spring means carried by said rotating shaft constantly urging said eccentric to turn with respect to said rotating shaft to a position of maximum eccentricity with respect thereto, the said torsional spring means permitting the said eccentric to turn to a position of less .than maximum eccentricity with respect to` the said rotating shaft responsive to pressure against which the pump operates.

10. A pump or compressor comprising a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a rotating shaft and an eccentric carried by said rotating shaft turnable with respect to the said rotating shaft during the-rotation thereof to positions of more or less eccentricity with respect thereto, said pistons being connected to said eccentric, resilient means constantly urging said eccentric to turn with respect to said rotating shaft to a position of maximum eccentricity with respect thereto, the said resilient means permitting the said eccentric to turn to a position of less than maximum eccentricity with respect to the said rotating shaft responsive to` pressure against which the pump operates, and means for adjusting the resiliencyv of the said resilient means whereby to vary the pump pressure responsive to lwhich the said eccentricity of the said eccentric becomes reduced.

11. In a pump or compressor, a plurality of radially disposed cylinders,l a piston reciprocat-l ingly mounted in each cylinder, a rotating shaft. means carried by and eccentric to said rotating shaft connected to said pistons for reciprocating the same, said eccentric means being turnable to positions of more or less eccentricity with respect to said rotating shaft, resilient means normally urging said eccentric means to a position of maximum eccentricity with respect to said rotating shaft causing said pistons to reciprocate at their maximum stroke, said eccentric means being turnable responsive to torque developed between said rotating, shaft and said eccentric means whereby to reduce the stroke at which said pistons reciprocate proportionately to the pressure against which said pump operates.

12. In a pump or compressor, a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a rotating shaft, means carried by and eccentric to said rotating shaft connected to said pistons for reciprocating the same, said eccentric means being turnable to positions of more or less eccentricity with respect to said rotatingv shaft, resilient means normallyurging said eccentric means to a position of maximum eccentricity with respect to said rotating shaft causing said pistons to reciprocate at their maximum stroke, said eccentric means being turnable responsive to torque developed between said rotating shaft and said eccentric means whereby to reduce the stroke at which said pistons reciprocate proportionately to the pressure against which said pump operates, and means for adjusting the resiliency of the said resilient means whereby to vary the torque responsive to which the stroke of the said pistons becomes reduced.

13. In a pump or compressor, a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a rotating shaft, eccentric means rotatable with said rotating shaft connected to said pistons for reciprocating said pistons, said eccentric means being turnable with respect to said rotating shaft to positions of more or less eccentricity with respect thereto whereby to vary the stroke of said pistons, spring means urging said eccentric means to a position of maximum eccentricity, said spring means being movable responsive to torque developed between said eccentric means and said rotating shaft to admit of the reduction of the eccentricity of the said eccentric means with respect to the said rotating shaft.

14. In a pump or compressor, a plurality of radially disposed cylinders, a piston reciprocatingly mounted in each cylinder, a rotating shaft. eccentric means rotatable with said rotating shaft connected to said pistons for reciprocating said pistons, said eccentric means being turnable4 with respect to said rotating shaft to positions of more or less eccentricity with respect thereto whereby to vary the stroke of said pistons, spring means urging said eccentric means to a position of maximum eccentricity, said spring means being movable responsive to torque developed between said eccentric means and said rotating shaft to admit of the reduction of the eccentricity of the saideccentric means with respect to the said rotating shaft, and means for adjusting the resiliency of the said spring means whereby to vary the, torque responsive to which the stroke of the said pistons becomes reduced.

oMAaE. CLARK. 

